CN112655070A

CN112655070A - Plasma source with lamp chamber calibration

Info

Publication number: CN112655070A
Application number: CN201980057387.5A
Authority: CN
Inventors: 张时雨; M·S·王; I·贝泽尔
Original assignee: KLA Tencor Corp
Current assignee: KLA Corp
Priority date: 2018-07-31
Filing date: 2019-07-29
Publication date: 2021-04-13
Anticipated expiration: 2039-07-29
Also published as: IL280237A; JP2021533406A; TWI808213B; JP2023159191A; WO2020028208A1; CN112655070B; TW202016975A; JP7330260B2; US10823943B2; KR102542726B1; US20200041774A1; KR20210027505A; IL280237B1; IL280237B2

Abstract

A plasma light source with lamp chamber calibration is disclosed. The system may include a pump source configured to generate pump illumination. The pumping illumination may be directed by an elliptical reflector element to an enclosed gas volume within a plasma lamp in order to generate a plasma. The plasma may be configured to produce broadband illumination. The system may also include a correction plate and/or an aspheric elliptical reflector element configured to alter the pumping illumination to correct aberrations introduced by the plasma lamp. The system may also include an additional aspheric correction plate configured to alter the broadband illumination to correct aberrations introduced by optical elements of the system.

Description

Plasma source with lamp chamber calibration

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the inventors of the present invention as "Shiyu Zhang", Mark Shi Wang, and elia berzel "in accordance with 35u.s.c. 119(e), U.S. provisional application serial No. 62/712,391 entitled PLASMA SOURCE LAMP HOUSE CORRECTION METHOD (PLASMA SOURCE LAMP HOUSE CORRECTION METHOD) filed on 31.7.2018, 7.31, which is incorporated herein by reference in its entirety.

Technical Field

The present invention relates generally to plasma-based light sources, and more particularly, to a plasma-based light source with lamp chamber aberration correction.

Background

As the demand for integrated circuits with smaller and smaller device features continues to increase, the need for improved illumination sources for inspecting these ever-shrinking devices continues to grow. One such illumination source includes a Laser Sustained Plasma (LSP) source. Laser sustained plasma light sources are capable of producing high power broadband illumination. Laser sustained plasma light sources operate by focusing laser radiation into an enclosed gas volume within a plasma lamp in order to excite the gas (e.g., argon or xenon) into a plasma state capable of emitting broadband illumination. This effect is commonly referred to as "pumping" the plasma.

The effectiveness of laser sustained light sources is based at least in part on the ability to generate a plasma in a compact, precisely known location. However, optical components within the laser sustained plasma light source (including the plasma lamp itself) can distort the pump laser radiation, requiring increased pump power and leading to thermal management problems. Distortion in the pump laser radiation can distort the focus of the pump source, thereby increasing plasma size, increasing system etendue, and reducing throughput. Furthermore, optical components within the laser-sustained plasma light source can also cause aberrations in the illumination generated by the plasma, resulting in difficulty in collecting the generated illumination and thereby reducing throughput.

Accordingly, it is desirable to provide a system and method that addresses one or more of the above-identified shortcomings.

Disclosure of Invention

A system in accordance with one or more embodiments of the present disclosure is disclosed. In one embodiment, the system includes a pump source configured to generate pump illumination. In another embodiment, the system includes a correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination so as to correct one or more aberrations of the pump illumination introduced by one or more optical elements of the system. In another embodiment, the system includes a reflector element configured to receive the pumping illumination and direct the pumping illumination to a gas volume enclosed within a plasma lamp, wherein the plasma lamp is configured to sustain a plasma within the gas volume to generate broadband illumination.

A system in accordance with one or more embodiments of the present disclosure is disclosed. In one embodiment, the system includes a broadband illumination source. The broadband illumination source may include: a pump source configured to generate pump illumination; a correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination; and a reflector element configured to receive the pumping illumination and direct the pumping illumination to an enclosed gas volume within the plasma lamp. In another embodiment, the plasma lamp is configured to sustain a plasma within the gas volume to produce broadband illumination. In another embodiment, the system includes a detector assembly. In another embodiment, the system includes a set of characterization optics configured to collect at least a portion of the broadband illumination from the broadband illumination source and direct the broadband illumination onto a sample. In another embodiment, the set of characterization optics is further configured to direct radiation from the sample to the detector assembly.

A system in accordance with one or more embodiments of the present disclosure is disclosed. In one embodiment, the system includes a pump source configured to generate pump illumination. In another embodiment, the system includes a first calibration plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination. In another embodiment, the system includes a reflector element configured to receive the pumping illumination and direct the pumping illumination to a gas volume enclosed within a plasma lamp. In another embodiment, the plasma lamp is configured to sustain a plasma within the gas volume to produce broadband illumination. In another embodiment, the system includes a second correction plate configured to receive the broadband illumination and correct one or more aberrations of the broadband illumination, wherein the second correction plate comprises an aspheric correction plate.

A system in accordance with one or more embodiments of the present disclosure is disclosed. In one embodiment, the system includes a broadband illumination source. In another embodiment, the broadband illumination source includes: a pump source configured to generate pump illumination; a first correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination; and a reflector element configured to receive the pumping illumination and direct the pumping illumination to an enclosed gas volume within the plasma lamp. In another embodiment, the plasma lamp is configured to sustain a plasma within the gas volume to produce broadband illumination. In another embodiment, the broadband illumination source includes a second correction plate configured to receive the broadband illumination and correct one or more aberrations of the broadband illumination. In another embodiment, the second correction plate comprises an aspheric correction plate. In another embodiment, the system includes a detector assembly. In another embodiment, the system includes a set of characterization optics configured to collect at least a portion of the broadband illumination from the broadband illumination source and direct the broadband illumination onto a sample, wherein the set of characterization optics is further configured to direct radiation from the sample to the detector assembly.

A method in accordance with one or more embodiments of the present disclosure is disclosed. In one embodiment, the method includes generating pump illumination. In another embodiment, the method includes correcting the pump illumination with a first correction plate. In another embodiment, the method includes collecting the pumping illumination with a reflector element and focusing the pumping illumination to an enclosed volume of gas within a plasma lamp. In another embodiment, the method includes generating a plasma within the gas volume enclosed within the plasma lamp. In another embodiment, the method includes generating broadband illumination with the plasma. In another embodiment, the method includes correcting one or more aberrations of the broadband illumination with a second correction plate.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not necessarily restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and together with the general description, serve to explain the principles of the invention.

Drawings

Many advantages of the present invention can be better understood by those skilled in the art by reference to the accompanying drawings, in which:

fig. 1A illustrates a plasma source having a lamp chamber correction system in accordance with one or more embodiments of the present disclosure;

fig. 1B illustrates a plasma source having a lamp chamber correction system in accordance with one or more embodiments of the present disclosure;

FIGS. 2A and 2B illustrate pump focus profile cross-sections near an elliptical reflector in a system with a cylindrical plasma lamp, in accordance with one or more embodiments of the present disclosure;

fig. 3A and 3B illustrate pump heat profile cross-sections at the focus of an elliptical reflector in a system with a cylindrical plasma lamp, in accordance with one or more embodiments of the present disclosure;

FIGS. 4A and 4B illustrate a collected thermal profile cross-section at the focus of an elliptical reflector in a system having a cylindrical plasma lamp, in accordance with one or more embodiments of the present disclosure;

fig. 5A and 5B illustrate pump focus profile cross-sections at the focus of an elliptical reflector in a system with an prolate spheroidal plasma lamp in accordance with one or more embodiments of the present disclosure;

fig. 6 illustrates a surface profile chart of an aspheric correction plate in accordance with one or more embodiments of the invention;

fig. 7A and 7B illustrate pump focus profile cross-sections at the focus of an elliptical reflector in a system with an prolate spheroidal plasma lamp in accordance with one or more embodiments of the present disclosure;

fig. 8 illustrates a surface profile chart of an aspheric correction plate in accordance with one or more embodiments of the invention;

fig. 9A and 9B illustrate a light collection focus profile cross-section at a light collection focus in a system having an prolate spheroidal plasma lamp in accordance with one or more embodiments of the present disclosure;

10A and 10B illustrate a light collection focus profile cross-section at a light collection focus in a system having an prolate spheroidal plasma lamp in accordance with one or more embodiments of the present disclosure;

fig. 11 illustrates a simplified schematic diagram of an optical characterization system implementing a plasma source with a lamp chamber correction system, in accordance with one or more embodiments of the present disclosure;

fig. 12 illustrates a simplified schematic diagram of an optical characterization system implementing a plasma source with a lamp chamber correction system, in accordance with one or more embodiments of the present disclosure; and

fig. 13 illustrates a flow diagram of a method for correcting errors induced by a plasma source lamp chamber in accordance with one or more embodiments of the invention.

Detailed Description

The present invention has been particularly shown and described with reference to certain embodiments and specific features thereof. The embodiments set forth herein are to be considered as illustrative and not restrictive. It will be readily apparent to persons skilled in the relevant art that various changes and modifications in form and detail can be made therein without departing from the spirit and scope of the invention.

Reference will now be made in detail to the disclosed subject matter as illustrated in the accompanying drawings.

Referring generally to fig. 1A-13, a plasma source and method with a lamp chamber correction system in accordance with one or more embodiments of the present disclosure are described.

Embodiments of the present invention relate to systems and methods for correcting errors attributable to components in a Laser Sustained Plasma (LSP) light source. More particularly, embodiments of the invention relate to systems and methods for correcting aberrations attributable to components in an LSP light source, including, but not limited to, compensators, plasma lamps, and the like. Additional embodiments of the present invention relate to the use of aspheric correction plates and/or aspheric reflector elements to modify the pump illumination of an LSP light source in order to correct aberrations attributable to components of the LSP light source. Additional embodiments of the invention relate to the use of an aspheric correction plate to modify broadband illumination produced by a plasma of an LSP light source in order to correct aberrations attributable to components of the LSP light source.

As previously mentioned herein, the optical components of the LSP light source can distort the pumping radiation/illumination of the LSP light source. The distortion in the pump radiation/illumination may require additional pump power to achieve the same throughput, leading to thermal management problems. In addition, the distorted pump radiation can distort the focus of the pump radiation, thereby increasing the size of the plasma, increasing the system etendue, and reducing the system throughput. Furthermore, optical components within the LSP light source can also cause aberrations in the broadband illumination generated by the plasma itself, resulting in difficulty in collecting the generated illumination and thereby reducing throughput.

For example, the LSP light source may utilize plasma lamps of different shapes, including, but not limited to, cylindrical plasma lamps, prolate spheroid plasma lamps (e.g., "rugby spheroid" plasma lamps), and the like. These plasma lamp configurations can distort the illumination entering and exiting the plasma lamp. These distortions and/or aberrations caused by the plasma lamp and other optical elements, if left uncorrected, can increase the power required by the LSP light source, reduce the effectiveness of the LSP light source, and reduce throughput. Accordingly, embodiments of the present invention relate to systems and methods for correcting aberrations caused by optical components of LSP light sources. Correction of aberrations within the LSP light source can reduce the required pumping power, produce a tighter, brighter plasma focus and improve the collection of illumination produced by the plasma.

Fig. 1A and 1B illustrate a plasma source having a lamp chamber correction system 100 in accordance with one or more embodiments of the present disclosure. In general, the system 100 may include a pump source 102, a lamp chamber 104, an entrance window 106, a cold mirror 116, a reflector element 110, and an exit window 120.

Fig. 1A illustrates a plasma source having a lamp chamber correction system 100 in accordance with one or more embodiments of the present disclosure. The system 100 may include, but is not limited to, a pump source 102 and a lamp chamber 104. The lamp chamber 104 may include, but is not limited to, an entrance window 106, a correction plate 108, a reflector element 110, a plasma lamp 112 configured to enclose a gas volume and generate a plasma 114, a cold mirror 116, an additional correction plate 118, and an exit window 120. In another embodiment, the system 100 may include one or more optical elements 122 and one or more downstream optical elements 124. It should be noted herein that the depicted configuration should not be considered limiting unless otherwise mentioned herein. In this regard, the system 100 may include additional/fewer optical elements than shown and described. By way of example, the additional correction plate 118 and the exit window 120 can be combined into a single component such that the additional correction plate 118 acts as the exit window.

In one embodiment, the pump source 102 is configured to generate the pump illumination 101 and direct the pump illumination 101 along the pump path 103. The pump source 102 may include any illumination source known in the art configured to pump a plasma, including, but not limited to, one or more lasers. For example, the pump source 102 may include one or more fiber lasers or any form of electrical energy known in the art. For example, the pump source 102 may include one or more 200 μm fiber lasers. By way of another example, the pump source 102 may include one or more infrared lasers. It is noted herein that for the purposes of the present invention, the terms "pump illumination 101" and "pump radiation 101" are used interchangeably unless otherwise mentioned herein. Furthermore, the term "pumping path 103" and similar terms may refer to the path taken by the pumping illumination 101 from the pumping source 102 to the plasma 114. The pump illumination 101 may include illumination/radiation of any wavelength or range of wavelengths known in the art, including, but not limited to, Infrared (IR) radiation, Near Infrared (NIR) radiation, Ultraviolet (UV) radiation, visible radiation, and the like.

In another embodiment, the pump illumination 101 enters the lamp chamber 104 via the entrance window 106. The entrance window 106 may include any optical element known in the art for transmitting illumination, including, but not limited to, one or more windows, one or more lenses, one or more terminals, and the like. In another embodiment, the pump illumination 101 is directed to the correction plate 108. The correction plate 108 may comprise a cylindrical correction plate. In one embodiment, the calibration plate 108 is configured to alter one or more characteristics of the pumping illumination 101. For example, the correction plate 108 may be configured to correct one or more aberrations of the pump illumination introduced by the optical elements of the system 100.

In another embodiment, the pump illumination 101 is directed to the reflector element 110. As shown in fig. 1A, the reflector element 110 may comprise an elliptical reflector element 110. However, unless mentioned herein, this should not be considered limiting as the elliptical reflector 110 elements may take any shape known in the art for directing the pumped illumination 101 to the plasma lamp 112. The reflector element 110 may be configured to receive the pumping illumination 101 and to direct the pumping illumination 101 to a gas volume enclosed within the plasma lamp 112 in order to generate a plasma 114 within the gas volume. The plasma lamp 112 may take any shape known in the art for enclosing a gas volume. For example, as shown in fig. 1A, the plasma lamp 112 may include a cylindrical plasma lamp 112. The cylindrical plasma lamp 112 may enclose a gas volume known in the art suitable for generating a plasma comprising any gas or gas mixture, including, but not limited to, xenon (Xe), argon (Ar), and the like. In one embodiment, the gas volume enclosed within cylindrical plasma lamp 112 may be enclosed at high pressure. For example, the gas volume within the cylindrical plasma lamp 112 may be at 10 atm.

As previously mentioned herein, plasma lamp 112 may distort pumped illumination 101 entering plasma lamp 112 and/or distort broadband illumination 107 (e.g., broadband radiation 107) generated by plasma 114 and exiting plasma lamp 112. Furthermore, additional optical elements of the system 100 may introduce additional distortion. These distortions may cause one or more aberrations in the broadband illumination 107 produced by the plasma, thereby reducing the effectiveness of the system 100 and reducing throughput. Aberrations introduced by the plasma lamp 112 and/or additional optical elements of the system 100 may be better understood with reference to fig. 2A and 2B.

Fig. 2A and 2B illustrate pump focus profile cross-sections near an elliptical reflector in a system 100 with a cylindrical plasma lamp 112, in accordance with one or more embodiments of the present disclosure. The irradiance of the focal profile in

graphs

200 and 202 is W/mm²Is expressed in units. As depicted in fig. 2A, graph 200 illustrates a pump focal point profile cross-section along the X-Y plane. As depicted in fig. 2B, graph 202 illustrates a pump focal point profile cross-section along the X-Z plane. As can be seen in fig. 2A and 2B, a cylindrical plasma lamp (e.g., cylindrical plasma lamp 112) may introduce a large amount of distortion/aberration near reflector element 110 (e.g., elliptical reflector element 110). By way of example, a 28 μm plasmonic sphere at the elliptical focus can be re-imaged to over 60mm at the pump focus. This level of distortion/aberration, if uncorrected, can result in reduced pumping efficiency, reduced collection efficiency of the broadband illumination 107, and reduced throughput.

Referring again to fig. 1A, reflector element 110 (e.g., elliptical reflector element 110) may be configured to correct one or more aberrations induced along pumping path 103 by plasma lamp 112 and/or additional optical elements. In one embodiment, reflector element 110 may comprise an odd-term aspheric reflector element that minimizes and/or reduces aberrations introduced by plasma lamp 112 and/or additional optical elements. In one embodiment, several odd aspheric terms may be added to reflector element 110 (e.g., elliptical reflector element 110) in order to correct for aberrations introduced by plasma lamp 112 (e.g., cylindrical plasma lamp 112). For example, a second order odd aspheric term may be added to reflector element 110. By way of another example, a sixth order odd aspheric term may be added to reflector element 110. Further by way of example, a hundred order odd aspheric term may be added to the reflector element.

The surface profile of an aspheric reflector element 110 (e.g., an aspheric elliptical reflector element 110) can be described by equation 1:

where k is the conic constant of the reflector element 110, c is the base radius of curvature, r is the radius of the reflector element 110, and a_iIs used for r_iIs a number, where i can be 1, 2,3, … n. In some embodiments, equation 1 may be simplified and expressed as equation 2:

the benefits achieved by using an aspheric reflector element 110 to correct for aberrations introduced along the pumping path 103 may be better understood with reference to fig. 3A and 3B.

Fig. 3A and 3B illustrate pump heat profile cross-sections at the focus of an elliptical reflector in a system 100 with a cylindrical plasma lamp 112, in accordance with one or more embodiments of the present disclosure.

Graphs

300, 302 illustrate the pump thermal profile cross section of a 28 μm plasma sphere at the focus of an elliptical reflector. Graph 300 (fig. 3A) illustrates a thermal profile cross-section of a system without an aspheric reflector element 110, and graph 302 (fig. 3B) illustrates a thermal profile cross-section of a system with an aspheric reflector element 110 that corrects for aberrations along the pumping path 103. Comparing fig. 3A and 3B, it can be seen that aspheric reflector element 110 may be capable of correcting aberrations introduced along pumping path 103 by cylindrical plasma lamp 112 and/or other optical elements. In some embodiments, the inclusion of an aspheric reflector element 110 can reduce the pumping thermal profile cross-section by more than sixty times.

As mentioned previously, the reflector element 110 may direct the pumping illumination 101 and focus the pumping illumination 101 into the enclosed gas volume within the plasma lamp 112 in order to generate the plasma 114. In another embodiment, the plasma 114 emits broadband illumination 107. The broadband illumination 107 may include illumination/radiation of various wavelengths, including, but not limited to, Ultraviolet (UV) radiation, Deep Ultraviolet (DUV) radiation, Vacuum Ultraviolet (VUV) radiation, and the like. The broadband illumination 107 may be directed through a cold mirror 116. The cold mirror 116 may include any optical element known in the art, including, but not limited to, a beam splitter, a sampler, a filter, and the like. In another embodiment, the cold mirror 116 directs the broadband illumination 107 along the collection path 105 to an additional correction plate 118. It should be noted herein that collection path 105 can be considered the path of broadband illumination 107 from plasma 114 to downstream optical element 124.

In another embodiment, the cold mirror 116 directs the broadband illumination 107 to an additional correction plate 118. In additional and/or alternative embodiments, the additional correction plate 118 may be configured to correct for any distortions and/or aberrations introduced along the collection path 105 in the broadband illumination 107. In this regard, the additional correction plate 118 may include an aspheric correction plate 118. For example, the additional correction plate 118 may include an odd-term aspheric correction plate 118. It should be noted herein that the use of an additional correction plate 118 in the collection path 105 may improve the correction of the broadband illumination 107 and thus increase the throughput and efficiency of the system 100.

The benefits of the additional correction plate 118 in correcting for distortions and/or aberrations introduced along the collection path 105 may be better understood with reference to fig. 4A and 4B.

Fig. 4A and 4B illustrate thermal profile cross-sections at the focus of an elliptical reflector in a system 100 with a cylindrical plasma lamp 112, in accordance with one or more embodiments of the present disclosure. The graph 400 of fig. 4A illustrates a thermal profile cross-section of a 28 μm plasma disk positioned at the focus of an ellipse. Similarly, graph 402 of FIG. 4B illustrates a thermal profile cross-section of a 28 μm plasma sphere positioned at the focus of an ellipse.

Reference will be made again to fig. 1A. In another embodiment, the broadband illumination 107 is directed along the collection path 105 to the exit window 120. The exit window 120 may include any optical element configured to allow the broadband illumination 107 to exit the lamp chamber 104, including, but not limited to, one or more windows, one or more lenses, one or more terminals, and the like. In another embodiment, broadband illumination 107 is directed along collection path 105 by one or more optical elements 122. The one or more optical elements 122 may include any optical element known in the art, including, but not limited to, one or more color filters, one or more lenses, one or more mirrors, one or more beam splitters, one or more prisms, and the like. In another embodiment, the one or more optical elements 122 direct the broadband illumination 107 to one or more downstream optical elements 124. The one or more downstream optical elements 124 may include any optical element known in the art for forming, collecting, or focusing the characterized illumination 109, including, but not limited to, one or more homogenizers, one or more polarizers, one or more beam shapers, and the like. The characterizing illumination 109 may be used in any downstream characterizing system (including, but not limited to, imaging systems, metrology systems, spectroscopy systems, and the like).

It should be noted herein that the order of the optical elements arranged along the pumping path 103 and/or the collection path 105 should not be considered limiting unless otherwise mentioned herein. For example, after being directed by the cold mirror 116, the broadband illumination 107 may exit the lamp housing 104 via the exit window 120 before interacting with the additional correction plate 118. Thus, unless otherwise mentioned herein, the order of the optical elements in fig. 1A is provided for illustration only.

Fig. 1B illustrates a plasma source lamp chamber correction system 100 in accordance with one or more embodiments of the present disclosure. The system 100 may include, but is not limited to, a pump source 102 and a lamp chamber 104. The lamp chamber 104 may include, but is not limited to, an entrance window 106, a compensator plate 126, a correction plate 128, a reflector element 110, a plasma lamp 130 (e.g., prolate spheroidal plasma lamp 130), a cold mirror 116, an additional correction plate 132, and an exit window 120. It should be noted herein that any description associated with fig. 1A may be considered applicable to fig. 1B, insofar as applicable, unless otherwise mentioned herein. Similarly, any description associated with fig. 1B may be considered applicable to fig. 1A, insofar as applicable, unless otherwise mentioned herein.

In one embodiment, as depicted in fig. 1B, the plasma lamp includes a substantially prolate spheroidal plasma lamp 130 (e.g., a substantially "football-shaped" plasma lamp 130). Similar to the case of cylindrical plasma lamp 112, it is noted herein that prolate spheroidal plasma lamp 130 may introduce aberrations into system 100. In systems in which the aberrations introduced by prolate spheroid plasma lamp 130 are not corrected, the pump laser power may be in the range of about 4 kilowatts (kW) to 7 kilowatts (kW). The aberrations introduced by prolate spheroidal plasma lamp 130 can be better understood with reference to fig. 5A.

Fig. 5A illustrates a pump focus profile cross-section at the focus of an elliptical reflector in a system 100 with an prolate spheroidal plasma lamp 130, in accordance with one or more embodiments of the present disclosure. The graph 500 depicted in FIG. 5A illustrates a pump focal point profile cross-section for a 200 μm fiber laser source. As can be seen in fig. 5A, prolate spheroidal plasma lamp 130 may introduce significant distortion and/or aberrations into system 100 that need to be corrected.

Reference will be made again to fig. 1B. In one embodiment, the system 100 includes a compensator plate 126. It should be noted herein that the compensator plate 126 may introduce distortions and/or aberrations into the system 100 that require correction in addition to plasma lamps (e.g., cylindrical plasma lamp 112, prolate spheroidal plasma lamp 130, and the like).

In another embodiment, the system 100 includes a calibration plate 128. It should be noted herein that unless otherwise mentioned herein, discussions regarding the correction plate 108 and the additional correction plate 118 may be considered applicable to the correction plate 128. In one embodiment, the correction plate 128 comprises an aspheric correction plate 128. The correction plate 128 (e.g., aspheric correction plate 128) may be configured to correct one or more aberrations and/or astigmatism introduced by the compensator plate 126, cold mirror 116, plasma lamp (e.g., prolate spheroidal plasma lamp 130), and the like. In one embodiment, the correction plate 128 may comprise a modified cylindrical correction plate. For example, correction plate 128 can be formed by adding up to a third order odd aspheric term on the back surface of cylindrical correction plate 108. In another embodiment, the correction plate 128 may include two separate correction plates: odd aspheric correctors and cylindrical correctors that may be configured to correct one or more aberrations and/or astigmatism introduced by the compensator plate 126, cold mirror 116, plasma lamp (e.g., prolate spheroidal plasma lamp 130), and the like. In yet another embodiment, the correction plate 128 may include a anamorphic profile that combines odd aspheric terms and cylindrical correction terms onto a single surface of the correction plate 128.

The aspheric profile of the correction plate 128 (e.g., aspheric correction plate 128) can be better understood with reference to fig. 6.

Fig. 6 illustrates a surface profile chart 600 of an aspheric correction plate (e.g., aspheric correction plate 128) in accordance with one or more embodiments of the invention. In one example, curve 602 of graph 600 may illustrate a surface profile of correction plate 128 (e.g., aspheric correction plate 128). It should be noted herein, however, that curve 602 is provided for illustration only and should not be considered as limiting the scope of the present invention unless otherwise mentioned herein.

The correction plate 128 can help correct for aberrations and/or astigmatism introduced into the system 100 along the pumping path 103. To further illustrate this effect, reference will be made again to fig. 5A and 5B.

Fig. 5A and 5B illustrate pump focus profile cross-sections at the focus of an elliptical reflector in a system 100 with an prolate spheroidal plasma lamp 130, in accordance with one or more embodiments of the present disclosure. More particularly, the graph 500 depicted in FIG. 5A illustrates a pump focus profile cross-section of a 200 μm fiber laser source that is not corrected by the correction plate 128. In contrast, the graph 502 depicted in FIG. 5B illustrates the pump focus profile cross section of the 200 μm fiber laser source corrected by the correction plate 128.

As can be seen in graph 502, for the calibrated 200 μm fiber laser source, the full width at half maximum (FWHM) of the cross section of the focal profile is about 20 μm. Furthermore, a 200 μm fiber laser source may be capable of providing approximately 4kW of power, and may therefore be sufficient for use in a wide range of LSP light sources even when calibrated with the calibration plate 128. Comparing graph 500 and graph 502, it can be appreciated that the corrected focal energy density (e.g., corrected with system 100) can be between ten and fifty-five times the uncorrected focal energy density. The level of improvement achieved by the system 100 may depend on many factors, including, but not limited to, the type of pump source 102, the manufacture of plasma lamps (e.g., cylindrical plasma lamp 112, prolate spheroidal plasma lamp 130, and the like), alignment tolerances, and the like.

Fig. 7A and 7B illustrate pump focus profile cross-sections at the focus of an elliptical reflector in a system 100 with an prolate spheroidal plasma lamp 130, in accordance with one or more embodiments of the present disclosure. More particularly, the graph 700 depicted in FIG. 6A illustrates a pump focus profile cross-section of a 600 μm fiber laser source that is not corrected by the correction plate 128. In contrast, the graph 702 depicted in FIG. 6B illustrates the pump focus profile cross-section of the 600 μm fiber laser source corrected by the correction plate 128. Comparing graph 700 to graph 702, the corrected focal energy density (e.g., corrected with system 100) is about 2.4 times the uncorrected focal energy density, indicating an improvement of about 140% for a 600 μm ray laser source.

It should be noted herein that the position of the pump source 102 can be adjusted in order to alter the position of the focal point of the pump illumination 101. For example, the tip of the fiber laser may be adjusted along the optical axis in order to change the position of the plasma 114. For example, moving the tip of the fiber laser approximately 6.4mm may cause the plasma 114 to move approximately 5.5 μm.

Reference will be made again to fig. 1B. After the correction plate 128, the pumping illumination 101 may be directed to the reflector element 110 (e.g., elliptical reflector element 110) along the pumping path 103. The reflector element 110 may be configured to receive the pumping illumination 101 and direct the pumping illumination 101 to a gas volume enclosed within the prolate spheroidal plasma lamp 130 in order to generate a plasma 114 within the gas volume. In another embodiment, the plasma 114 generates broadband illumination 107, including, but not limited to, Ultraviolet (UV) illumination, Deep Ultraviolet (DUV) illumination, Vacuum Ultraviolet (VUV) illumination, and the like.

In another embodiment, the cold mirror 116 can direct the broadband illumination 107 along the collection path 105 to an additional correction plate 132. In additional and/or alternative embodiments, the additional correction plate 132 may be configured to correct any distortions and/or aberrations introduced in the broadband illumination 107 by optical elements along the collection path 105, including, but not limited to, the prolate spheroidal plasma lamp 130. In this regard, the additional correction plate 132 may include an aspheric correction plate 132. For example, the additional correction plate 132 may include an odd-term aspheric correction plate 132. It should be noted herein that the use of an additional correction plate 132 in the collection path 105 may improve the correction of the broadband illumination 107 and thus increase the throughput and efficiency of the system 100.

It is further noted herein that unless otherwise mentioned herein, discussions associated with the correction plate 108, the additional correction plate 118, and the correction plate 128 can be considered applicable to the additional correction plate 132. Thus, in one embodiment, up to a third order odd aspheric term may be added to the additional correction plate 132 to correct aberrations introduced by the prolate spheroidal plasma lamp 130. Further, it is noted herein that the surface profile of the additional correction plate 132 may be described by equation 1 or equation 2.

The benefits of the additional correction plate 132 in correcting for distortion and/or aberrations introduced in the system 100 including the prolate spheroidal plasma lamp 130 may be better understood with reference to fig. 8, 9A and 9B.

Fig. 8 illustrates a surface profile chart 800 of an additional correction plate 132 (e.g., an aspheric correction plate 132) in accordance with one or more embodiments of the invention. In one example, curve 802 of graph 800 may illustrate a surface profile of an additional correction plate 132 (e.g., aspheric correction plate 132). It should be noted herein, however, that curve 802 is provided for illustration only and should not be considered as limiting the scope of the present invention unless otherwise mentioned herein.

Fig. 9A and 9B illustrate a collected focus profile cross-section at a corrected focus in a system 100 having an prolate spheroidal plasma lamp 130, in accordance with one or more embodiments of the present disclosure. The graph 900 depicted in fig. 9A illustrates a collected light focus profile cross section of a 20 μm plasmonic ball source that is not corrected by the aspheric correction plate 132. In contrast, the graph 902 depicted in fig. 9B illustrates the pump focus profile cross section of the 20 μm plasma sphere source corrected by the aspheric correction plate 132.

Fig. 10A and 10B illustrate a light collection focus profile cross-section at a light collection focus in a system having an prolate spheroidal plasma lamp, in accordance with one or more embodiments of the present disclosure. The graph 1000 depicted in fig. 10A illustrates a collected light focus profile cross section of a 200 μm plasmonic ball source that is not corrected by the aspheric correction plate 132. In contrast, the graph 1002 depicted in fig. 10B illustrates a pump focus profile cross section of the 200 μm plasma sphere source corrected by the aspheric correction plate 132.

Comparing fig. 9A and 9B and fig. 10A and 10B, it can be seen that correcting for broadband illumination 107 along collection path 105 can greatly improve the collection efficiency of system 100.

Fig. 11 illustrates a simplified schematic diagram of an optical characterization system 200 implementing the plasma source lamp chamber correction system 100, in accordance with one or more embodiments of the present disclosure. In one embodiment, the system 1100 includes the system 100, the illumination arm 203, the collection arm 205, the detector assembly 214, and the controller 218 including the one or more processors 220 and the memory 222.

It should be noted herein that the system 1100 may comprise any imaging, inspection, metrology, lithography, or other characterization system known in the art. In this regard, the system 1100 may be configured to perform inspection, optical metrology, lithography, and/or any form of imaging on the sample 207. Sample 207 may comprise any sample known in the art including, but not limited to, a wafer, a reticle/photomask, and the like. It should be noted that the system 1100 may incorporate one or more of the various embodiments of the system 100 described throughout this disclosure.

In one embodiment, sample 207 is disposed on stage assembly 212 to facilitate movement of sample 207. The stage assembly 212 may include any stage assembly 212 known in the art including, but not limited to, an X-Y stage, an R-theta stage, and the like. In another embodiment, stage assembly 212 is capable of adjusting the height of sample 207 during inspection or imaging to maintain focus on sample 207.

In another embodiment, illumination arm 203 is configured to direct characterizing illumination 109 from system 100 to sample 207. The illumination arm 203 may include any number and type of optical components known in the art. In one embodiment, the illumination arm 203 includes one or more optical elements 202, a beam splitter 204, and an objective lens 206. In this regard, the illumination arm 203 may be configured to focus the characterizing illumination 109 from the system 100 onto the surface of the sample 207. The one or more optical elements 202 may include any optical element or combination of optical elements known in the art, including, but not limited to, one or more mirrors, one or more lenses, one or more polarizers, one or more gratings, one or more filters, one or more beam splitters, and the like.

In another embodiment, the collection arm 205 is configured to collect light reflected, scattered, diffracted, and/or emitted from the sample 207. In another embodiment, the collection arm 205 can direct and/or focus the light from the sample 207 to the sensor 216 of the detector assembly 214. It should be noted that the sensor 216 and detector assembly 214 may include any sensor and detector assembly known in the art. The sensors 216 may include, but are not limited to, Charge Coupled Device (CCD) detectors, Complementary Metal Oxide Semiconductor (CMOS) detectors, Time Delay Integration (TDI) detectors, photomultiplier tubes (PMTs), Avalanche Photodiodes (APDs), and the like. Further, the sensor 216 may include, but is not limited to, a line sensor or an electron bombarded line sensor.

In another embodiment, the detector assembly 214 is communicatively coupled to a controller 218 that includes one or more processors 220 and memory 222. For example, the one or more processors 220 may be communicatively coupled to the memory 222, wherein the one or more processors 220 are configured to execute a set of program instructions stored on the memory 222. In one embodiment, the one or more processors 220 are configured to analyze the output of the detector assembly 214. In one embodiment, the set of program instructions is configured to cause the one or more processors 220 to analyze one or more characteristics of the sample 207. In another embodiment, the set of program instructions is configured to cause the one or more processors 220 to modify one or more characteristics of the system 1100 in order to maintain focus on the sample 207 and/or the sensor 216. For example, the one or more processors 220 may be configured to adjust the objective 206 or the one or more optical elements 202 in order to focus the characterizing illumination 109 from the system 100 onto the surface of the sample 207. By way of another example, the one or more processors 220 may be configured to adjust the objective 206 and/or the one or more optical elements 210 so as to collect illumination from the surface of the sample 207 and focus the collected illumination on the sensor 216.

It should be noted that the system 1100 may be configured in any optical configuration known in the art, including but not limited to dark field configurations, bright field orientations, and the like.

It should be noted herein that one or more components of system 1100 may be communicatively coupled to various other components of system 1100 in any manner known in the art. For example, the system 100, the detector assembly 214, the controller 218, and the one or more processors 220 may be communicatively coupled to each other and to other components via wired connections (e.g., copper wires, fiber optic cables, and the like) or wireless connections (e.g., RF coupling, IR coupling, data network communications (e.g., WiFi, WiMax, bluetooth, and the like)).

Fig. 12 illustrates a simplified schematic diagram of an optical characterization system 1200 arranged in a reflectance measurement and/or ellipsometry configuration, in accordance with one or more embodiments of the present disclosure. It should be noted that the various embodiments and components described with reference to fig. 11 may be construed as extending to the system of fig. 12. System 1200 may include any type of metering system known in the art.

In one embodiment, the system 1200 includes the system 100, the illumination arm 316, the collection arm 318, the detector assembly 328, and the controller 218 that includes one or more processors 220 and memory 222.

In this embodiment, characterizing illumination 109 from system 100 is directed to sample 207 via illumination arm 316. In another embodiment, the system 1200 collects radiation emitted from the sample via the collection arm 318. The illumination arm path 316 may include one or more beam adjustment components 320 adapted to modify and/or adjust the characterized illumination 109. For example, the one or more beam conditioning components 320 may include, but are not limited to, one or more polarizers, one or more filters, one or more beam splitters, one or more diffusers, one or more homogenizers, one or more apodizers, one or more beam shapers, or one or more lenses.

In another embodiment, the illumination arm 316 may utilize a first focusing element 322 to focus and/or direct the characterizing illumination 109 onto the specimen 207 disposed on the sample stage 212. In another embodiment, the collection arm 318 may include a second focusing element 326 that collects radiation from the sample 207.

In another embodiment, detector assembly 328 is configured to capture radiation emitted from sample 207 through collection arm 318. For example, detector assembly 328 may receive radiation reflected or scattered (e.g., via specular reflection, diffuse reflection, and the like) from sample 207. By way of another example, detector assembly 328 can receive radiation (e.g., luminescence associated with absorption of light beam 105, and the like) generated by sample 207. It should be noted that detector assembly 328 may include any sensor and detector assembly known in the art. The sensors may include, but are not limited to, CCD detectors, CMOS detectors, TDI detectors, PMTs, APDs, and the like.

The collection arm 318 may further include any number of collection beam conditioning elements 330 to direct and/or modify the illumination collected by the second focusing element 326, including, but not limited to, one or more lenses, one or more filters, one or more polarizers, or one or more phase plates.

The system 1200 may be configured as any type of metrology tool known in the art, such as, but not limited to, a spectroscopic ellipsometer with one or more illumination angles, a spectroscopic ellipsometer for measuring Mueller (Mueller) matrix elements (e.g., using a rotary compensator), a single wavelength ellipsometer, an angle-resolved ellipsometer (e.g., a beam profile ellipsometer), a spectroscopic reflectometer, a single wavelength reflectometer, an angle-resolved reflectometer (e.g., a beam profile reflectometer), an imaging system, a pupil imaging system, a spectroscopic imaging system, or a scatterometer.

Descriptions of inspection/metrology tools suitable for implementation in various embodiments of the present invention are provided in the following: U.S. patent application No. 13/554,954 entitled "Wafer Inspection System" filed on 7/9/2012; U.S. published patent application 2009/0180176 entitled "Split Field Inspection System Using Small Camera Inspection objects" published in 2009, 7/16; U.S. published patent application 2007/0002465 entitled "Beam Delivery System for Laser Dark-Field Illumination in Catadioptric Optical System" published on 4.1.2007; U.S. Pat. No. 5,999,310 entitled "Ultra-Wide band UV Microscope Imaging System with Wide Range Zoom Capability" (published 12/7 1999); U.S. patent 7,525,649 entitled "Surface Inspection System Using Laser Line Illumination with Two-Dimensional Imaging" issued on 28.4.2009; U.S. published patent application 2013/0114085 entitled "Dynamically Adjustable Semiconductor Metrology System" published by Wang (Wang) et al and 2013, 5/9; U.S. patent 5,608,526 entitled "Focused Beam Spectroscopic Ellipsometry Method and System (Focused Beam Spectroscopic Ellipsometry Method and System)" issued by Piwanka-Corle et al on 3/4 1997; and U.S. patent 6,297,880 entitled "Apparatus for Analyzing multilayer Thin Film Stacks on Semiconductors" (Apparatus for Analyzing Multi-Layer Thin Film Stacks on Semiconductors) "issued by Rosencwig et al, 10.2.2001, each of which is incorporated herein by reference in its entirety.

The one or more processors 220 of the present disclosure may include any one or more processing elements known in the art. To this extent, the one or more processors 220 can include any microprocessor-type device configured to execute software algorithms and/or instructions. It should be recognized that the steps described throughout this disclosure may be performed by a single computer system or, alternatively, by multiple computer systems. In general, the term "processor" may be broadly defined to encompass any device having one or more processing elements and/or logic elements that execute program instructions from the non-transitory memory medium 222. Moreover, different subsystems of the various systems disclosed may include processors and/or logic elements adapted to perform at least a portion of the steps described throughout this disclosure.

The memory medium 222 may include any storage medium known in the art suitable for storing program instructions executable by the associated processor(s) 220. For example, the memory medium 222 may comprise a non-transitory memory medium. For example, the memory medium 222 may include, but is not limited to, read-only memory, random-access memory, magnetic or optical memory devices (e.g., disks), magnetic tape, solid-state drives, and the like. In another embodiment, memory 222 is configured to store one or more results and/or outputs of the various steps described herein. It should be further noted that the memory 222 may be housed in a common controller housing with the one or more processors 220. In alternative embodiments, memory 222 may be remotely located with respect to the physical location of the one or more processors 220. For example, the one or more processors 220 may access a remote memory (e.g., a server) accessible over a network (e.g., the internet, an intranet, and the like). In this regard, the one or more processors 222 of the controller 218 may perform any of the various process steps described throughout this disclosure.

In some embodiments, the

systems

100, 1100, and 1200 as described herein may be configured as "stand-alone tools," which are interpreted herein as tools that are not physically coupled to a process tool. In other embodiments, such an inspection or metrology system may be coupled to a process tool (not shown) through a transmission medium that may enclose a seal line and/or a wireless portion. The process tool may comprise any process tool known in the art, such as a photolithography tool, an etching tool, a deposition tool, a polishing tool, a plating tool, a cleaning tool, or an ion implantation tool. The results of the inspections or measurements performed by the systems described herein may be used to alter parameters of a process or process tool using feedback control techniques, feed forward control techniques, and/or in-situ control techniques. The parameters of the process or the process tool may be altered manually or automatically.

Embodiments of

systems

100, 1100, and 1200 may be further configured as described herein. Additionally,

systems

100, 1100, and 1200 may be configured to perform any other steps of any of the method embodiments described herein.

Fig. 13 illustrates a flow diagram of a method 1300 for correcting errors induced by a plasma source lamp chamber, in accordance with one or more embodiments of the invention. It should be noted herein that the steps of method 1300 may be implemented in whole or in part by system 100. However, it should be further appreciated that the method 1300 is not limited to the system 100, as additional or alternative system-level embodiments may carry out all or part of the steps of the method 1300.

In step 1302, pump illumination is generated. For example, the pump source 102 can be configured to generate the pump illumination 101 and direct the pump illumination 101 along the pump path 103. The pump source 102 may include any illumination source known in the art configured to pump a plasma, including, but not limited to, one or more lasers, one or more fiber lasers, one or more Infrared (IR) lasers, and the like.

In step 1304, the pump illumination is corrected with a first correction plate. For example, the pump illumination 101 may be corrected by a cylindrical correction plate 108, as illustrated in fig. 1A. By way of another example, the pump illumination 101 may be corrected by an aspheric correction plate 128. As previously mentioned herein, correction of the pump illumination 101 by a correction plate (e.g., correction plates 108, 128) may be practiced to correct one or more aberrations introduced by one or more optical elements of the system 100, including, but not limited to, the

plasma lamps

112, 130.

In step 1306, the pump illumination is collected with a reflector element and focused to an enclosed gas volume within the plasma lamp. For example, the reflector element 110 may be configured to receive the pumping illumination 101 and direct the pumping illumination 101 to the enclosed gas volume within the plasma lamp 112. The reflector element 110 may comprise an elliptical reflector element. Further, reflector element 110 may comprise an aspheric reflector element 110. The plasma lamp 112 may take any shape known in the art for enclosing a gas volume. For example, as shown in fig. 1A, the plasma lamp 112 may include a cylindrical plasma lamp 112. By way of another example, the plasma lamp may comprise an prolate spheroidal plasma lamp 130, as shown in fig. 1B. The

plasma lamps

112, 130 may enclose a gas volume known in the art suitable for generating a plasma comprising any gas or gas mixture, including, but not limited to, xenon (Xe), argon (Ar), and the like. In one embodiment, the gas volume enclosed within the

plasma lamp

112, 130 may be enclosed at high pressure. For example, the gas volume within the

plasma lamps

112, 130 may be at 10 atm.

In step 1308, a plasma is generated within the enclosed gas volume within the plasma lamp. When the reflector element 110 collects the pumping illumination 110 and focuses the pumping illumination 110 into the enclosed gas volume within the

plasma lamp

112, 130, a plasma 114 may be generated within the gas volume.

In step 1310, broadband illumination is generated by the plasma. The broadband illumination 107 may include illumination/radiation of various wavelengths, including, but not limited to, Ultraviolet (UV) radiation, Deep Ultraviolet (DUV) radiation, Vacuum Ultraviolet (VUV) radiation, and the like.

In step 1312, one or more aberrations of the broadband illumination are corrected with a second correction plate. For example, the broadband illumination 107 may be directed to the

additional correction plates

118, 132, wherein the

additional correction plates

118, 132 are configured to correct one or more aberrations of the broadband illumination 107. In some embodiments, the

additional correction plates

118, 132 comprise aspheric correction plates.

Those skilled in the art will recognize that the components (e.g., operations), devices, objects, and the discussion accompanying them are described herein as examples and that various configuration modifications are contemplated for the sake of conceptual clarity. Thus, as used herein, the specific examples set forth and the accompanying discussion are intended to be representative of their more general classes. In general, the use of any particular example is intended to indicate its class, and the absence of particular components (e.g., operations), devices, and objects should not be taken as limiting.

Those skilled in the art will appreciate that there are a variety of carriers (e.g., hardware, software, and/or firmware) that can implement the processes and/or systems and/or other techniques described herein, and that the preferred carrier will vary with the context in which the processes and/or systems and/or other techniques are deployed. For example, if an implementer determines that speed and accuracy are paramount, the implementer may opt for a mainly hardware and/or firmware vehicle; alternatively, if flexibility is paramount, the implementer may opt for a primary software implementation; or yet again alternatively, the implementer may opt for some combination of hardware, software, and/or firmware. Thus, there are several possible vehicles by which the processes and/or devices and/or other techniques described herein can be accomplished, any of which is inherently less preferred over the other in that any vehicle to be utilized is a choice dependent upon the context in which it is to be deployed and the particular considerations of the implementer, e.g., speed, flexibility or predictability, any of which may vary.

The previous description is presented to enable one of ordinary skill in the art to make and use the invention as provided in the context of a particular application and its requirements. As used herein, directional terms (e.g., "top," "bottom," "above," "below," "upper," "upward," "lower," "below," and "downward") are intended to provide relative positions for purposes of description and are not intended to specify an absolute frame of reference. Various modifications to the described embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments. Thus, the present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

With respect to substantially any plural and/or singular terms used herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. For clarity, various singular/plural permutations are not set forth explicitly herein.

All methods described herein may include storing results of one or more steps of a method embodiment in memory. The results may include any of the results described herein and may be stored in any manner known in the art. The memory may comprise any memory described herein or any other suitable storage medium known in the art. After the results have been stored, the results may be accessed in memory and used by any of the method or system embodiments described herein; formatted for display to a user; by another software module, method or system, and the like. Further, the results may be stored "permanently," "semi-permanently," "temporarily," or for a period of time. For example, the memory may be Random Access Memory (RAM), and the results may not necessarily be retained indefinitely in the memory.

It is further contemplated that each of the embodiments of the method described above may include any other step of any other method described herein. Additionally, each of the embodiments of the method described above may be performed by any of the systems described herein.

The subject matter described herein sometimes illustrates different components contained within, or connected with, other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures can be implemented which achieve the same functionality. Conceptually, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as "associated with" each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being "connected," or "coupled," to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being "couplable," to each other to achieve the desired functionality. Specific examples that may be coupled include, but are not limited to, physically matable and/or physically interacting components, and/or wirelessly interactable and/or wirelessly interacting components, and/or logically interacting and/or logically interactable components.

Furthermore, it is to be understood that the invention is defined by the appended claims. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," and the like). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that: a claim recitation by the indefinite articles "a" or "an" limits any particular claim that encloses the recitation of such introduced claim to only one such recitation, even if the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the use of definite articles in the introduction to the claims is equally applicable. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations" (without other modifiers) typically means at least two recitations, or two or more recitations). Moreover, in instances where a conventional expression analogous to "at least one of A, B and C, and the like" is used, such construction is generally intended in the sense of the conventional expression as would be understood by one of ordinary skill in the art (e.g., "a system having at least one of A, B and C" would include, but not be limited to, systems that have a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B and C together, and the like). In instances where a convention analogous to "A, B or at least one of C, and the like" is used, such construction is generally intended in the sense the convention would be understood by those skilled in the art (e.g., "a system having at least one of A, B or C" would include, but not be limited to, systems that have a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B and C together, and the like). It should be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in implementation, claims, or drawings, should be understood to encompass the following possibilities: including one of the items, any one of the items, or both. For example, the phrase "a or B" will be understood to include the possibility of "a" or "B" or "a and B".

It is believed that the present invention and many of its attendant advantages will be understood by the foregoing description, and it will be apparent that various changes may be made in the form, construction and arrangement of the components without departing from the disclosed subject matter or without sacrificing all of its material advantages. The form described is merely illustrative and it is the intention of the appended claims to encompass and include such changes. Furthermore, it is to be understood that the invention is defined by the appended claims.

Claims

1. A system, comprising:

a pump source configured to generate pump illumination;

a correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination so as to correct one or more aberrations of the pump illumination introduced by one or more optical elements of the system; and

a reflector element configured to receive the pumping illumination and direct the pumping illumination to an enclosed gas volume within a plasma lamp, wherein the plasma lamp is configured to sustain a plasma within the gas volume to generate broadband illumination.

2. The system of claim 1, wherein the plasma lamp comprises a cylindrical plasma lamp.

3. The system of claim 1, wherein the reflector element comprises an aspheric reflector element.

4. The system of claim 3, wherein the surface profile of the aspheric reflector element is given by the equation

A description is given.

5. The system of claim 1, wherein the plasma lamp comprises a substantially prolate spheroidal plasma lamp.

6. The system of claim 1, wherein the correction plate comprises an aspheric correction plate configured to correct one or more aberrations of the pump illumination introduced by the plasma lamp.

7. The system of claim 6, wherein the surface profile of the correction plate is given by the equation

A description is given.

8. The system of claim 1, further comprising a compensator plate configured to receive the pump illumination and direct the pump illumination toward the reflector element.

9. The system of claim 1, further comprising one or more optical elements and a homogenizer, wherein the one or more optical elements are configured to receive the broadband illumination from the plasma lamp and direct the broadband illumination to the homogenizer.

10. The system of claim 1, wherein the pump source comprises a fiber laser pump source.

11. The system of claim 1, further comprising a cold mirror configured to receive the broadband illumination and direct the broadband illumination to a second correction plate.

12. The system of claim 1, wherein the correction plate comprises a first correction plate and a second correction plate, wherein the first correction plate includes one or more odd aspheric correction terms and the second correction plate includes one or more cylindrical correction terms.

13. The system of claim 1, wherein the correction plate includes a surface having one or more odd aspheric correction terms and one or more cylindrical correction terms.

14. A system, comprising:

a broadband illumination source, wherein the broadband illumination source comprises:

a pump source configured to generate pump illumination;

a correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination; and

a reflector element configured to receive the pumping illumination and direct the pumping illumination to an enclosed gas volume within a plasma lamp, wherein the plasma lamp is configured to sustain a plasma within the gas volume to generate broadband illumination;

a detector assembly; and

a set of characterization optics configured to collect at least a portion of the broadband illumination from the broadband illumination source and direct the broadband illumination onto a sample, wherein the set of characterization optics is further configured to direct radiation from the sample to the detector assembly.

15. The system of claim 14, wherein the plasma lamp comprises a cylindrical plasma lamp.

16. The system of claim 14, wherein the reflector element comprises an aspheric reflector element.

17. The system of claim 14, wherein the surface profile of the reflector element is given by the equation

A description is given.

18. The system of claim 14, wherein the plasma lamp comprises a substantially prolate spheroidal plasma lamp.

19. The system of claim 14, wherein the correction plate comprises an aspheric correction plate configured to correct one or more aberrations of the pump illumination introduced by the plasma lamp.

20. The system of claim 19, wherein the surface profile of the correction plate is given by the equation

A description is given.

21. The system of claim 14, further comprising a compensator plate configured to receive the pump illumination and direct the pump illumination toward the reflector element.

22. The system of claim 14, further comprising one or more optical elements and a homogenizer, wherein the one or more optical elements are configured to receive the broadband illumination from the plasma lamp and direct the broadband illumination to the homogenizer.

23. The system of claim 14, wherein the pump source comprises a fiber laser pump source.

24. The system of claim 14, further comprising a cold mirror configured to receive the broadband illumination and direct the broadband illumination to a homogenizer.

25. The system of claim 14, wherein the correction plate comprises a first correction plate and a second correction plate, wherein the first correction plate includes one or more odd aspheric correction terms and the second correction plate includes one or more cylindrical correction terms.

26. The system of claim 14, wherein the correction plate includes a surface having one or more odd aspheric correction terms and one or more cylindrical correction terms.

27. A system, comprising:

a pump source configured to generate pump illumination;

a first correction plate configured to receive the pump illumination and modify one or more characteristics of the pump illumination;

a reflector element configured to receive the pumping illumination and direct the pumping illumination to an enclosed gas volume within a plasma lamp, wherein the plasma lamp is configured to sustain a plasma within the gas volume to generate broadband illumination; and

a second correction plate configured to receive the broadband illumination and correct one or more aberrations of the broadband illumination, wherein the second correction plate comprises an aspheric correction plate.

28. The system of claim 27, wherein the plasma lamp comprises a cylindrical plasma lamp.

29. The system of claim 27, wherein the reflector element comprises an aspheric reflector element.

30. The system of claim 29, wherein the surface profile of the aspheric reflector element is given by the equation

A description is given.

31. The system of claim 27, wherein the plasma lamp comprises a substantially prolate spheroidal plasma lamp.

32. The system of claim 27, wherein the first correction plate comprises an aspheric correction plate configured to correct one or more aberrations of the pump illumination introduced by the plasma lamp.

33. The system of claim 32, wherein the surface profile of the first correction plate is given by the equation

A description is given.

34. The system of claim 27, further comprising a compensator plate configured to receive the pump illumination and direct the pump illumination toward the reflector element.

35. The system of claim 27, wherein the surface profile of the second correction plate is given by the equation

A description is given.

36. The system of claim 27, further comprising one or more optical elements and a homogenizer, wherein the one or more optical elements are configured to receive the broadband illumination from the second correction plate and direct the broadband illumination to the homogenizer.

37. The system of claim 27, wherein the pump source comprises a fiber laser pump source.

38. The system of claim 27, further comprising a cold mirror configured to receive the broadband illumination and direct the broadband illumination to the second correction plate.

39. A system, comprising:

a pump source configured to generate pump illumination;

a second correction plate configured to receive the broadband illumination and correct one or more aberrations of the broadband illumination, wherein the second correction plate comprises an aspheric correction plate;

a detector assembly; and

40. The system of claim 39, wherein the plasma lamp comprises a cylindrical plasma lamp.

41. The system of claim 39, wherein the reflector element comprises an aspheric reflector element.

42. The system of claim 39, wherein the surface profile of the reflector element is given by the equation

A description is given.

43. The system of claim 39, wherein the plasma lamp comprises a substantially prolate spheroidal plasma lamp.

44. The system of claim 39, wherein the first correction plate comprises an aspheric correction plate configured to correct one or more aberrations of the pump illumination introduced by the plasma lamp.

45. The system of claim 44, wherein the surface profile of the first correction plate is given by the equation

A description is given.

46. The system of claim 39, further comprising a compensator plate configured to receive the pump illumination and direct the pump illumination toward the reflector element.

47. The system of claim 39, wherein the surface profile of the aspheric correction plate is given by the equation

A description is given.

48. The system of claim 39, further comprising one or more optical elements and a homogenizer, wherein the one or more optical elements are configured to receive the broadband illumination from the aspheric correction plate and direct the broadband illumination to the homogenizer.

49. The system of claim 39, wherein the pump source comprises a fiber laser pump source.

50. The system of claim 39, further comprising a cold mirror configured to receive the broadband illumination and direct the broadband illumination to the aspheric correction plate.

51. A method, comprising:

generating pump illumination;

calibrating the pump illumination with a first calibration plate;

collecting and focusing the pumping illumination with a reflector element to an enclosed gas volume within a plasma lamp;

generating a plasma within the gas volume enclosed within the plasma lamp;

generating broadband illumination with the plasma; and

correcting one or more aberrations of the broadband illumination with a second correction plate.

52. The method of claim 51, wherein the plasma lamp comprises a cylindrical plasma lamp.

53. The method of claim 51, wherein the reflector elements comprise aspheric reflector elements.

54. The method of claim 51, wherein the surface profile of the reflector element is given by the equation

A description is given.

55. The method of claim 51, wherein the plasma lamp comprises a substantially prolate spheroidal plasma lamp.

56. The method of claim 51, wherein the first correction plate comprises an aspheric correction plate configured to correct one or more aberrations of the pump illumination introduced by the plasma lamp.

57. The method of claim 56, wherein the surface profile of the first correction plate is given by the equation

A description is given.

58. The method of claim 51, further comprising compensating the pump illumination with a compensator plate.

59. The method of claim 51, further comprising directing the broadband illumination to a homogenizer via one or more optical elements.

60. The method of claim 51, wherein the generating pump illumination comprises generating pump illumination with a fiber laser pump source.